How to monitor the 12V battery's health?

[Londondrug]

I use leaf spy pro to read it. It is sometimes 15.6V, and sometimes 14V or 13V. Isn't the 12V battery maximum reading is 12.5V? I am so confused how to monitor it with leafspy.

One day when I turned on the screen to scan radio stations, the battery icon on the screen show only 2 bars out of 4 bars. Does it mean that it needs be charged and get attention? I stopped scanning right away.

 

[knightmb]

The battery icon on the radio is that of the blue-tooth phone it is paired with, not the EV battery.

LeafSpy shows you the real-time 12V battery voltage, but that changes when you are driving as different accessories put different loads on the system (cabin fan, radio, heaters, etc.)

If you want LeafSpy to get a more stable reading, wait until you have not been driving the Leaf for a few hours. Then use LeafSpy to get a reading without actually starting the Leaf in drive mode.

You do this by first making sure every single accessory is off. No seat heaters, cabin fans, radio, lights, etc. Do this before you shut off your EV if you intend to measure the 12V battery later. Then while in your Leaf, start LeafSpy. It will complain that it can't get any data (because the Leaf is off obviously). Without putting your foot on the brake, start the Leaf into "standby" mode by pressing the power button twice in a row. The first press is just ACC mode for the radio/power ports, the second press will light up the dash and allow other accessory use (thought not recommended since that will just drain the 12V directly). In this test, it's ok to do this though as we only want to get a reading on the 12V battery. With everything off (mostly), you should hopefully see a battery voltage that is higher than 12.0 V, hopefully a lot more. If you see a voltage less than 12.0 V, it's possible the battery is just freezing (if you are doing this in freezing weather temperatures) or it may be the sign of a 12V battery in decline.

 

[Londondrug]

The battery icon on the radio is that of the blue-tooth phone it is paired with, not the EV battery.

LeafSpy shows you the real-time 12V battery voltage, but that changes when you are driving as different accessories put different loads on the system (cabin fan, radio, heaters, etc.)

If you want LeafSpy to get a more stable reading, wait until you have not been driving the Leaf for a few hours. Then use LeafSpy to get a reading without actually starting the Leaf in drive mode.

You do this by first making sure every single accessory is off. No seat heaters, cabin fans, radio, lights, etc. Do this before you shut off your EV if you intend to measure the 12V battery later. Then while in your Leaf, start LeafSpy. It will complain that it can't get any data (because the Leaf is off obviously). Without putting your foot on the brake, start the Leaf into "standby" mode by pressing the power button twice in a row. The first press is just ACC mode for the radio/power ports, the second press will light up the dash and allow other accessory use (thought not recommended since that will just drain the 12V directly). In this test, it's ok to do this though as we only want to get a reading on the 12V battery. With everything off (mostly), you should hopefully see a battery voltage that is higher than 12.0 V, hopefully a lot more. If you see a voltage less than 12.0 V, it's possible the battery is just freezing (if you are doing this in freezing weather temperatures) or it may be the sign of a 12V battery in decline.

Thanks a lot, very well explained.

 

[Snakebitten]

Sitting in the Lazyboy in the RV.
The Leaf is parked about 20' away.

I have a Bluetooth 12V voltage meter/logger mounted to the Leaf battery. (~$25) I can get a reading on its "resting state" without disturbing the car or waking up the OBD for LeafSpy

Here it is about 4 minutes ago:

 

[nlspace]

i would charge that thang to 100% and keep it there at all times.

 

[Bombastinator2]

I use leaf spy pro to read it. It is sometimes 15.6V, and sometimes 14V or 13V. Isn't the 12V battery maximum reading is 12.5V? I am so confused how to monitor it with leafspy.

One day when I turned on the screen to scan radio stations, the battery icon on the screen show only 2 bars out of 4 bars. Does it mean that it needs be charged and get attention? I stopped scanning right away.

Batteries are a bit like balloons. A NiMh 3.7v battery for example, is generally between 4.2 and 2.5 depending on how charged it is and when whatever drawing off it says “nope not enough power” I’ve seen that from 2.7-3.0v. They’re listed as “3.7v nominal” though. I suspect the “12v” on a 12v is the nominal rather than actual voltage. I don’t know what it varies between.
This is why some AAs might no longer work in a Walkman (yes. I’m an old) but still work in a flashlight if not terribly well.
I don’t know how much charge the LEAF systems need to do their thing using the 12v, but below whatever that is, you've got a problem. The impression I get is it is somewhat higher than average. You can check the voltage with the app (total cost was around $50 to get it for me. The app and a dongle you plug in below the steering wheel are required) or you can check it with a multimeter under the hood.

 

[hradek]

The battery icon on the radio is that of the blue-tooth phone it is paired with, not the EV battery.

LeafSpy shows you the real-time 12V battery voltage, but that changes when you are driving as different accessories put different loads on the system (cabin fan, radio, heaters, etc.)

If you want LeafSpy to get a more stable reading, wait until you have not been driving the Leaf for a few hours. Then use LeafSpy to get a reading without actually starting the Leaf in drive mode.

You do this by first making sure every single accessory is off. No seat heaters, cabin fans, radio, lights, etc. Do this before you shut off your EV if you intend to measure the 12V battery later. Then while in your Leaf, start LeafSpy. It will complain that it can't get any data (because the Leaf is off obviously). Without putting your foot on the brake, start the Leaf into "standby" mode by pressing the power button twice in a row. The first press is just ACC mode for the radio/power ports, the second press will light up the dash and allow other accessory use (thought not recommended since that will just drain the 12V directly). In this test, it's ok to do this though as we only want to get a reading on the 12V battery. With everything off (mostly), you should hopefully see a battery voltage that is higher than 12.0 V, hopefully a lot more. If you see a voltage less than 12.0 V, it's possible the battery is just freezing (if you are doing this in freezing weather temperatures) or it may be the sign of a 12V battery in decline.

I have never seen a battery rea

The battery icon on the radio is that of the blue-tooth phone it is paired with, not the EV battery.

LeafSpy shows you the real-time 12V battery voltage, but that changes when you are driving as different accessories put different loads on the system (cabin fan, radio, heaters, etc.)

If you want LeafSpy to get a more stable reading, wait until you have not been driving the Leaf for a few hours. Then use LeafSpy to get a reading without actually starting the Leaf in drive mode.

You do this by first making sure every single accessory is off. No seat heaters, cabin fans, radio, lights, etc. Do this before you shut off your EV if you intend to measure the 12V battery later. Then while in your Leaf, start LeafSpy. It will complain that it can't get any data (because the Leaf is off obviously). Without putting your foot on the brake, start the Leaf into "standby" mode by pressing the power button twice in a row. The first press is just ACC mode for the radio/power ports, the second press will light up the dash and allow other accessory use (thought not recommended since that will just drain the 12V directly). In this test, it's ok to do this though as we only want to get a reading on the 12V battery. With everything off (mostly), you should hopefully see a battery voltage that is higher than 12.0 V, hopefully a lot more. If you see a voltage less than 12.0 V, it's possible the battery is just freezing (if you are doing this in freezing weather temperatures) or it may be the sign of a 12V battery in decline.

I have never seen a battery reading in my Leaf over 12 volts, even when the battery is new. That is not true of other cars I have owned. The higher reading I do see is during the charge cycle. The best way of looking at the health of the house battery is to pop the hood and read the voltage with a volt meter an hour or so after you shut the car off or charged the car. When you see standing voltages near 11 volts it is time to carry one of these around in the car.

NOCO Boost Plus GB40 1000A UltraSafe Car Battery Jump Starter, 12V Battery Pack, Battery Booster, Jump Box, Portable Charger​

 

[Bombastinator2]

I have never seen a battery rea

I have never seen a battery reading in my Leaf over 12 volts, even when the battery is new. That is not true of other cars I have owned. The higher reading I do see is during the charge cycle. The best way of looking at the health of the house battery is to pop the hood and read the voltage with a volt meter an hour or so after you shut the car off or charged the car. When you see standing voltages near 11 volts it is time to carry one of these around in the car.

NOCO Boost Plus GB40 1000A UltraSafe Car Battery Jump Starter, 12V Battery Pack, Battery Booster, Jump Box, Portable Charger​

That’s one way to do it I guess. I’ve seen minimum good battery claimed now at 11 and 13v. I kinda want to know what the actual minimum is at this point.

 

[Snakebitten]

Since it has been established on my 2022 F150 Powerboost that strange things start to happen once the resting voltage drops below 12.3V, I use that as my threshold for the Leaf as well. Afterall, they both are laden with critical electronic modules.

My 5 year old (2018) Leaf 12V battery is barely holding its head at that level. It certainly requires daily driving and nightly L2 charging to keep it at 12.3v or better. So I'm getting close to visiting my local NAPA for a quality East Penn AGM for it.

 

[RYoungberg]

The battery icon on the radio is that of the blue-tooth phone it is paired with, not the EV battery.

LeafSpy shows you the real-time 12V battery voltage, but that changes when you are driving as different accessories put different loads on the system (cabin fan, radio, heaters, etc.)

If you want LeafSpy to get a more stable reading, wait until you have not been driving the Leaf for a few hours. Then use LeafSpy to get a reading without actually starting the Leaf in drive mode.

You do this by first making sure every single accessory is off. No seat heaters, cabin fans, radio, lights, etc. Do this before you shut off your EV if you intend to measure the 12V battery later. Then while in your Leaf, start LeafSpy. It will complain that it can't get any data (because the Leaf is off obviously). Without putting your foot on the brake, start the Leaf into "standby" mode by pressing the power button twice in a row. The first press is just ACC mode for the radio/power ports, the second press will light up the dash and allow other accessory use (thought not recommended since that will just drain the 12V directly). In this test, it's ok to do this though as we only want to get a reading on the 12V battery. With everything off (mostly), you should hopefully see a battery voltage that is higher than 12.0 V, hopefully a lot more. If you see a voltage less than 12.0 V, it's possible the battery is just freezing (if you are doing this in freezing weather temperatures) or it may be the sign of a 12V battery in decline.

Thanks, great tutorial.

 

[mrlithium]

my 2019 leaf's battery wont hold a charge, so, I looked at Napa agm, $228 + tax = $244
with 3 yr warranty vs a LiFepo4 from LithiumMoto for $250 with 4 yr warranty.

 

[hradek]

That’s one way to do it I guess. I’ve seen minimum good battery claimed now at 11 and 13v. I kinda want to know what the actual minimum is at this point.

Having experienced it, about 10.8 volts before you need to boost before driving.

 

[cornbinder89]

On a car battery, when they die from old age, there is really no warning, when they die from sulfation they may stuggle under load, but not give much if any warning.
So if you are looking for a 100% surefire way not to get caught out with a dead car, carry a charged jumper box or jumper cables, there is no 100% way to know when it is not going to work the next time you try.
With my large deep cycle packs, I monitored current in and out, as well as voltage under those loads. I could see the results in front of my face I can even tell when one of the batteries had "bad cell" in a multi battery bank with 24 or more cells.
An installed voltmeter and ammeter on the dash, along with a person who could understand what the gauges are telling, would be one way, but most would not know what to watch for.

 

[hradek]

my 2019 leaf's battery wont hold a charge, so, I looked at Napa agm, $228 + tax = $244
with 3 yr warranty vs a LiFepo4 from LithiumMoto for $250 with 4 yr warranty.

I went with an AGM from Pep Boys but sold that car and bought a new Leaf so don't have a clue if it was an upgrade, I will probably go with AGM again when the warranty runs out on my third battery because of the fire hazard of a lithium in a circuit that is overcharging. If they made a deep cycle that fit, I would give that a try but I think the AGM is the closest thing to that.

 

[mrlithium]

overcharging ? ... overcharging a lead acid produces hydrogen gas, so, you have a choice; fire or explosion ! ha

 

[cornbinder89]

overcharging ? ... overcharging a lead acid produces hydrogen gas, so, you have a choice; fire or explosion ! ha

Charging a LA will disassociate water into hydrogen and oxygen and can, if severally overcharged can collect enough to cause a small explosion. It can blow apart the case and is mainly a risk from the remaining acid that gets thrown out. The "event" is short lived and self extinguishing.
A lithium battery can go in the thermal run-a-way when overcharged, and is self feeding until the battery has consumed itself, a much longer and hotter even that can spread.
It is why all LI batteries of any size have a BMS to prevent it. Both can cause damage if over charged, but of the two the Li event is far more dangerous. Both are safe if handled correctly

 

[knightmb]

I will probably go with AGM again when the warranty runs out on my third battery because of the fire hazard of a lithium in a circuit that is overcharging.

A modern Lithium has a BMS that prevents that, but even if you remove the BMS, the "charged" voltage of a Lithium is higher (14.6V) than the "charged" voltage of a SLA or AGM (14V) and the danger zone is so high that you won't find a vehicle alternator that is trying to charge pass 16V. The Leaf has a max of 15V in an open circuit. So while what you see in the news about batteries catching on fire in laptops and phones or the occasional news article about some EV somewhere in the world caught on fire, is missing a lot of context. When you over-charge both Lithium and SLA/AGM batteries, they don't just sprout fire. Other than capacity damage to the battery, they start to warm up and eventually you reach the point of no return. Lithium like what is used in phones or your EV can start to burn like a candle, but so can SLA/AGM once the plastic case catches fire. There is an advantage to a particulator Lithium, the LiFePO4 used in starter batteries that we often refere to here are much more resistant to catching fire than the other Lithium chemistries. If you were to bypass the BMS on these and purposely over-charge them, the battery will actually start leaking and along with the horrible smell, it might leak enough to avoid catching on fire. It depends on how much over-charging you refer too. A lightning bolt amount of energy or a malfunctiong charge system that is stuck on max.

Basically, I wouldn't worry about the fire hazard when choosing a 12V battery in regards to the LiFePO4 chemistry. A lot of things have to go wrong to get one of those to catch fire.

 

[hradek]

overcharging ? ... overcharging a lead acid produces hydrogen gas, so, you have a choice; fire or explosion ! ha

I am not sure this is a real problem since the battery is quite small, current load is low and the battery is not enclosed in a small area.. The only thing I am certain of is that every time I charge the big lithium batteries and every time I start the car the house 12 volt battery goes through charge cycles. When I get home the battery is at its "resting voltage". I would define resting voltage as the actual voltage the battery can hold after being charged which can be measured 10 or 15 minutes after you get home and should be close to what you see the next morning. For some reason this resting voltage declines over time faster than any of my previous cars. I have never measured anything below 10 which is to say unlike my other cars the batteries never were dead and could easily be jumped to get the car working but the batteries were unreliable. The other cars all had alternators that took over the function of the battery and you could easily drive a car with a bad battery. What I don't know is what is happening when I drive this car. It must be able to supply 12 volts in real time from the big lithium batteries and does this function the same way as the alternator did on my other cars? I have owned over 10 cars and most of those 12 volt batteries lasted over six years before requiring replacements. None of them had the physical appearance of liquid under the battery caps I see on this car.but none of them had such a small battery. So maybe size does matter?

 

[cornbinder89]

The answer is when you start, drive and charge your car a DC to DC converter charges your 12 volt from your traction battery power or charger power.
https://mynissanleaf.com/threads/le...-suspect-12v-battery.35018/page-2#post-639340
The above thread goes into a deep dive on the whole system.
There should be electrolyte under the caps, in the cells, but not on the surface of the case, water should be added to bring the level to the bottom of the "tube" on the cell port. This is the same as it has been for batteries for over a century. If someone over fills the cells, it will expand when it warms from charging and be forced out under the cap. These are FLA (Flooded Lead Acid) cells, not SLA (Sealed Lead Acid) cells. A "sealed" battery has no caps to remove and no way to add water if needed.
It does not function like are car alternator. Most of those (it is changing in recent years) have one fixed voltage setting that the alternator puts out the whole time the car is running. The Leaf and some more sophisticated devices for charging storage batteries use a multi stage protocol to charge. It allows better and more complete recharge in less time, but does require a good read on the battery voltage.
You want to see 14.5 volts when the car is first turned on (or when the wipers are on) and once the system detects the charge current to the battery has reached the correct setting (when the current starts to drop going into the battery) it tapers the voltage back to "float" level and the converter is carrying the full load of 12 volt things running and the battery is not seeing much if any current going in or out. Float voltage will be around 13.1-13.2 volts measured at the battery posts.

 

[Bombastinator2]

TLDNR: musing about linguistic stuff
Hmmm. Technically it’s not a traction battery it’s a tracktOR battery it doesn’t assist magnetically or something it actually does the twisting. This is how farm tractors got their name btw. The first ones didn’t even turn by themselves and required a team of horses in front. They simply helped pull. TractOR engines (though they were sometimes called traction engines too). Can’t call them tractor batteries because everyone would ask where the tractor is as the word has turned into a noun.